EVE 280A Load Capacity Testing Help Wanted

Stepandwolf

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How long are the cables between the tester and the battery terminals?
about 14"....there is no voltage drop between the battery and the terminals on the tester. The high quality 10ga wire isn't causing any voltage loss.
 

Bud Martin

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There will always be Voltage drops when current flows on the wire since wire is conductor which has resistance.
 

Just John

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about 14"....there is no voltage drop between the battery and the terminals on the tester. The high quality 10ga wire isn't causing any voltage loss.
With that length and the short distance, there won't be much voltage drop, but there will always be some. That's why I suggested setting low voltage as 2.3v (that's what I used with 10 gauge). That is not why your tester won't let you pull 20 amps. I'm not sure why you can't pull 20 amps, but 10 gauge wire isn't the problem. I suggest limiting to 15 amps, because when I first started trying these testers out (I've tried 4 different manufacturers and models), everyone was saying the MOSFET will blow. So far I've not had one blow, however every one has the diode right next to the MOSFET get incredibly hot, like 100 degrees Celsius hot, measured through the fiberglass PCB. That's boiling water, and you can get a burn. While checking the MOSFET temperature, trust me, I noticed.

Anyway, they all would go up to 20 amps, and most would even let you dial it a little beyond (like 21-22 amps). I don't recommend running it that high, just because that part gets so hot, not because you can't. I'm not sure why yours won't.
 

Bud Martin

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Mine is ATORCH 150W, when I first use I could not get to 20A using 10AWG 15", I was able to get to 20A after cutting the wire to 6" but I had to put the unit on a stand to the same height as the battery, it ran for about 5 minute at 20A before blowing up the MOSFET.
I replaced the MOSFET and run it at 15A after that. The diode next to the MOSFET does get hot but I found that the heatsink does not really make contact with the body of the diode, the diode body thickness is less that the MOSFET, so I installed the silicone thermal pad to fill the gap. My tester has been working good and I had tested 12 cells so far with no issue.
 

Stepandwolf

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Hi guys...thanks for all of the advice and suggestions, but if I have to rebuild the unit to go from 12.3 to 15a, sorry, but it isn't worth it to me, and if I start to modify it, it will likely get broken. I do have a replacement coming so if I delay the return of this one, I will have two for a while, but with a 10A PS, I am discharging quicker than I am charging. I just finished charging the third battery which is now on the tester and finished testing the second battery, and the 4th is now on the charger.

For the test of the 2nd battery, which was supposed to be the highest A of the 8, I set the LVCO to 2.30A which is what you mentioned John, but my reason was that the meter is off. I just set the 3rd battery test for 2.2v cut off and I bet that will still leave the battery above 2.5v.

Anyway, with the cut-off at 2.3, the test ran the same 23.5 hours and ended at 287.5A with 2.58V. I think I was able to squeeze more out of the first battery because I went from 2.5 to 2.4 to 2.3 and gained 2-3 more each step. Going right to 2.3 (really 2.58) gave me slightly less than I had hoped for the battery that supposedly started with more A, 291 vs. 289 so I was a little disappointed, but still happy with 2.87.5.
 

Stepandwolf

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There will always be Voltage drops when current flows on the wire since wire is conductor which has resistance.
By "no voltage drop" I meant measurable on my meter. When my meter says 3.61 at one end of the wire and 3.61 at the other end of the wire, that to me is zero, knowing there was a v drop I couldn't measure.
 

Just John

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Hi guys...thanks for all of the advice and suggestions, but if I have to rebuild the unit to go from 12.3 to 15a, sorry, but it isn't worth it to me, and if I start to modify it, it will likely get broken. I do have a replacement coming so if I delay the return of this one, I will have two for a while, but with a 10A PS, I am discharging quicker than I am charging. I just finished charging the third battery which is now on the tester and finished testing the second battery, and the 4th is now on the charger.

For the test of the 2nd battery, which was supposed to be the highest A of the 8, I set the LVCO to 2.30A which is what you mentioned John, but my reason was that the meter is off. I just set the 3rd battery test for 2.2v cut off and I bet that will still leave the battery above 2.5v.

Anyway, with the cut-off at 2.3, the test ran the same 23.5 hours and ended at 287.5A with 2.58V. I think I was able to squeeze more out of the first battery because I went from 2.5 to 2.4 to 2.3 and gained 2-3 more each step. Going right to 2.3 (really 2.58) gave me slightly less than I had hoped for the battery that supposedly started with more A, 291 vs. 289 so I was a little disappointed, but still happy with 2.87.5.
To be honest, there is very little capacity down that low, and with higher amps, the cell/battery will warm up considerably down that low voltage area. If it gets to 280, I'd stop and call it good (since it did meet spec).

I just wanted to make sure the extended storage time didn't harm the cells, and it obviously did not. You got what you paid for, no need to try and get every last drop out of them. :cool:
 

Stepandwolf

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To be honest, there is very little capacity down that low, and with higher amps, the cell/battery will warm up considerably down that low voltage area. If it gets to 280, I'd stop and call it good (since it did meet spec).

I just wanted to make sure the extended storage time didn't harm the cells, and it obviously did not. You got what you paid for, no need to try and get every last drop out of them. :cool:
Did I just get what I paid for or did I get what anyone could expect ordering a Grade A "matched" cell. Is there something else I should suggest to someone else who is looking? Thanks
 

Bud Martin

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So far you are getting the capacity at higher than what the spec rating of the cell, 280Ah, I would just use them and be happy that you get more than 280Ah out of them and you did not have wait for months to get them either.
 

Stepandwolf

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So far you are getting the capacity at higher than what the spec rating of the cell, 280Ah, I would just use them and be happy that you get more than 280Ah out of them and you did not have wait for months to get them either.
It is partly an experiment...what is the capacity, did I get the 291 they were spec'd at? If I am going to consider what I have done a sampling, should I stop and not test them all? I am compelled to test all 8 of the EVE and go back and test the Lishen which were never tested.

Thanks
 

Bud Martin

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I think if you have this kind of tester/charger that tells you how much you pumping to the battery and how much you are pulling out from battery and with repeatable setting for charging and discharging you may see different result.

You can also see the effect of absorption
 

Just John

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Did I just get what I paid for or did I get what anyone could expect ordering a Grade A "matched" cell. Is there something else I should suggest to someone else who is looking? Thanks
Grade A means they perform up to spec (i.e. 280AH or above). Matched really means more when placed in a pack and high rates of charge/discharge are applied to the pack. That means the cell voltages track very closely through the full range. Most people here don't really need matched cells, although it certainly means they will perform better and likely last much longer. It also means that the tiny balance current supplied by most BMS is either superfluous, or more than adequate.

You certainly got what you paid for, in my opinion.
 

Stepandwolf

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I think if you have this kind of tester/charger that tells you how much you pumping to the battery and how much you are pulling out from battery and with repeatable setting for charging and discharging you may see different result.

You can also see the effect of absorption
Yes, for much more money and it works until the PS supply takes out the voltage regulator in the tester as it did with Andy's :) The average consumer that doesn't get beer donations like Andy can't justify buying any load testers, even $50 ones. If there hasn't been a suspicion about these batteries, I wouldn't have bought a tester. Just like when I bought the Lishen 272As from Michael. I assumed they were grade A and would meet spec so I didn't get a tester. Now that I have it, and since I never used the batteries, I will test them too.

For those keeping track, I have finished testing the third battery. 286.55A with 2.6V left. That is the lowest one so far, but not by much, and as you said Bud, over spec for the battery.

Thanks
 

Just John

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It is partly an experiment...what is the capacity, did I get the 291 they were spec'd at? If I am going to consider what I have done a sampling, should I stop and not test them all? I am compelled to test all 8 of the EVE and go back and test the Lishen which were never tested.

Thanks
Remember, the 291AH was tested in the factory under controlled conditions. They use that mainly for matching cells. I also see that Eve only guarantees grade A cells to pull full capacity (280AH) within a month of shipping from the factory, or the first 5 cycles. There is an initial drop in capacity the first 10 cycles or so, but it does level off after that. They don't guarantee you will get 291AH, rather they guarantee you will get at least 280AH capacity, and even that is very much depending on test conditions, temperature, amps used, etc.
 

Stepandwolf

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Grade A means they perform up to spec (i.e. 280AH or above). Matched really means more when placed in a pack and high rates of charge/discharge are applied to the pack. That means the cell voltages track very closely through the full range. Most people here don't really need matched cells, although it certainly means they will perform better and likely last much longer. It also means that the tiny balance current supplied by most BMS is either superfluous, or more than adequate.

You certainly got what you paid for, in my opinion.
Both Luyuan and Basen claim these are matched cells and the spreadsheet data they are providing is supposed to indicate they are matched without actually saying it on the spreadsheet. Don't think anyone has contested Amy calling the cells matched, and multiple people refer to her spreadsheet data as conclusive proof. I am wondering if the three columns on the spreadsheet with the small range of voltages has something to do with the matching, i.e. shows "close values" after multiple tests.
 

Stepandwolf

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Remember, the 291AH was tested in the factory under controlled conditions. They use that mainly for matching cells. I also see that Eve only guarantees grade A cells to pull full capacity (280AH) within a month of shipping from the factory, or the first 5 cycles. There is an initial drop in capacity the first 10 cycles or so, but it does level off after that. They don't guarantee you will get 291AH, rather they guarantee you will get at least 280AH capacity, and even that is very much depending on test conditions, temperature, amps used, etc.
Haven't seen where they wrote that. If they build a battery in December (as they did mine and Mr.Proton) and ship them to the customer (Basen and Luyuan) in June and July, they theoretically couldn't sell them as matched. Technically they could sell them as "were matched", but if they aren't matched after a month...then...
 

Just John

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Yes, for much more money and it works until the PS supply takes out the voltage regulator in the tester as it did with Andy's :) The average consumer that doesn't get beer donations like Andy can't justify buying any load testers, even $50 ones. If there hasn't been a suspicion about these batteries, I wouldn't have bought a tester. Just like when I bought the Lishen 272As from Michael. I assumed they were grade A and would meet spec so I didn't get a tester. Now that I have it, and since I never used the batteries, I will test them too.

From reading others reviews of what they received using the group buy, I would say you are MUCH more likely to have received grade A cells.
Most vendors on Aliexpress and Alibaba are buying factory rejects and slapping labels on them saying grade A, when they are not (and even worse, the seller KNOWS they are not grade A).

With the group buy, the vendors/sellers have a vested interest in delivering high quality cells, because Michael will send more orders their way, and drop anyone who is delivering obviously fraudulent cells. Incentives work.
 

Just John

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Both Luyuan and Basen claim these are matched cells and the spreadsheet data they are providing is supposed to indicate they are matched without actually saying it on the spreadsheet. Don't think anyone has contested Amy calling the cells matched, and multiple people refer to her spreadsheet data as conclusive proof. I am wondering if the three columns on the spreadsheet with the small range of voltages has something to do with the matching, i.e. shows "close values" after multiple tests.
Yes, besides capacity, those three ranges show the IR of the cells at different states of charge, and are a key component of cell matching for high current use. The capacity (other than the lowest one is your pack capacity) is not as big a part. Basically the IR tells you how much the individual cell voltage drops under high current, every cell will drop voltage under high current, and they are matching how much. Once the current is dropped, they will all "bounce" back, the matching makes sure they do it evenly. Not a big concern for low current use like for solar storage.
 

Just John

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Haven't seen where they wrote that. If they build a battery in December (as they did mine and Mr.Proton) and ship them to the customer (Basen and Luyuan) in June and July, they theoretically couldn't sell them as matched. Technically they could sell them as "were matched", but if they aren't matched after a month...then...
It depends on which version of the spec sheet you read. The version I purchased has it, but I see the later versions have dropped it.

5.1 Standard Test Conditions
Test should be conducted with new batteries within one month after shipment from our factory and the cells shall not be cycled more than five times before the test. Unless otherwise defined, test stated in this specification should be conducted at temperature of 25±2℃, humidity 45~85% and Test should be performed under standard atmospheric conditions with 86KPa~106KPa pressure.


This is not for matched, this is for grade A. Matched cells should remain matched for their entire life, it is different than grade A. Certainly "matched" implies grade A when new, but cells can still be matched after use as long as the set is used as a set evenly.
 
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